Posted by John Walker on February 02, 2001 at 17:45:15:
In Reply to: Some O2 questions posted by mattschechter on February 02, 2001 at 15:23:22:
Matt, all your doing with the oxygen is displacing molecule. The sportt diving community uses a partial pressure of .16 to a partial pressure of 1.6 as a safe limit persay, but their are other factors involved.
Oxygen toxicity is dose and time respondent. Hypoxia (the lask of oxygen to body tissues) is primarally dose respondent. As far as a safe limit goes, it could be a ppO2 of 1.6 or much less depending on factors involved such as workload, temperature, time, stress and more.
I'm not sure I understood your comment "yet there isn't enough O2 to be useful to a human fror breathing". These numbers represent Partial Pressures (pp). That is the fraction of O2 multiplied by the absoluted atmospheric pressure based on ATA.
For example: Air will have a ppO2 of 1.4 at 187 feet salt water. (see Chris, I have a calculator also). At the surface air has a PO2 of .21
Really though, go by Scuba Toys and tell Jim you would like to learn more about this stuff. Its fun as well as interesting. And I think Jim is a wonderful instructor.
JW